The Shanghai lockdown has been extended indefinitely, a move that casts further uncertainty over Chinese supply chains, as new data is published showing the impact on China’s ocean freight volumes.The severe restrictions in the eastern half of the city, including Pudong, were due to be lifted on Friday, but nearly all areas remain under lockdown and local authorities have given no timeframe for its end, other than saying it would be done “in stages”.And one forwarder told The Loadstar: “Shanghai has started another round of mass-[Covid] testing, with the whole city population of 25 million being tested.“We’re promised that anyone with a negative test will be free and positive cases will be moved into quarantine centres, as before. Let’s see if they will keep their promises finall...